SPHEREx Preliminary Mission Overview

The Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx) mission is part of the NASA Astrophysics Medium Explorer (MIDEX) program and will perform the first near-infrared all-sky spectral survey from a Low Earth, sun-synchronous, polar orbit. As a space-based observatory, SPHEREx will use spectroscopy to measure hundreds of millions of galaxies and a diversity of astronomical phenomena. With this capability, SPHEREx will produce a three-dimensional map of the universe, which scientists will use to answer questions about the early universe, the history of galaxies, and the prevalence of life-sustaining molecules in planet-forming regions of space. Relying on a robust instrument design with a single observing mode, SPHEREx will map the entire sky four times during its 25-month on-orbit survey period. It will survey the sky in optical, as well as near-infrared light, specifically obtaining near-infrared
$0.75-5.0\ \mu\mathrm{m}$
spectra every 6″ over the entire sky. SPHEREx is designed for strong scientific synergies with other missions and observatories, with a resulting goal of a rich legacy archive of data that can be used by the community on numerous scientific investigations. SPHEREx is managed by the Jet Propulsion Laboratory—a division of California Institute of Technology—for NASA's Science Mission Directorate in Washington, DC. The mission's Principal Investigator is based at Caltech, which is also developing the payload in collaboration with JPL. Ball Aerospace is supplying the spacecraft bus. The Korea Astronomy and Space Science Institute (KASI) is an instrument and science partner for the mission. Data will be processed and archived at Caltech's IPAC. In addition to scientists from Caltech, JPL, and KASI, the scientific analysis will include scientists from numerous institutions. This paper provides a preliminary overview of the mission and its concept of operation, as well as an overview of the design of the observatory's spacecraft bus, the instrument, the software architecture, the mission system, and the ground data system. A curated list of key and driving design trade studies are also presented. It is expected that subsequent planned publications will provide intermediate project updates and eventual science results from on-orbit operations.